Psychtoolbox: Trying to create a vector that determines whether responses were correct or not

I'm having issues with determining whether a response is correct on my experiment. For context my experiment requires the subject to make a choice about the number of dots after being presented with stimuli that requires using either the left or right arrow key for 10 trials. Whenever I check response_correct, it always shows up as NaN with no assigned value. Is there something I'm missing? Here's a snippet of the code:

response_correct = NaN (numTrials,1);
for i = 1:numTrials
    rnd\_num = rand();
    
    if rnd_num < 0.5
    	numDot = randi([1 50], 1, 1);
        
    else
    	numDot = randi([50 100], 1, 1);
        
    end

:::::::::::::::::::::::::::::::::::

    dotts(i)= numDot;
    answered = 1;
    
    if (keyIsDown) 
        key = KbName(find(keyCode)); 
        response_key {i} = key;
        response_time(i) = time;
        dotts(i)= numDot;
        answered = 1;
        
        if dotts(i) == randi([1 50], 1, 1) && strcmp(response_key{i},'k')==1
        	response_correct(i) = 1; % it's correct
            
        elseif dotts(i) == randi([1 50], 1, 1) && strcmp(response_key{i},'d') ==1
        	response_correct(i) = 0;
            
        elseif dotts(i) == randi([50 100], 1, 1) && strcmp(response_key{i},'k') ==1
        	response_correct(i) = 0;
            
        elseif dotts(i) == randi([50 100], 1, 1) && strcmp(response_key{i},'d') ==1
        	response_correct(i) = 1;
            
        end
        results_response_correct = response_correct;
        
    end

Answer 1

[Walter Roberson]

Odd, I am certain that I showed someone how to solve this problem already. If I recall correctly, that person deleted their query and my response, which I understood to mean that they had solved the problem (perhaps with my help) and no longer needed to ask about it.

response_correct = NaN (numTrials,1);
for i = 1:numTrials
    if rand() < 0.5
    	numDot = randi([1 50], 1, 1);
        expected_key = 'k';
    else
    	numDot = randi([50 100], 1, 1);
        expected_key = 'd';
    end
    
    dotts(i) = numDot;
    
    answered = false;
    
    %at this point you should be either looping waiting for a response
    %possibly with a timeout, or else asking psychtoolbox to read a key,
    %possibly with a timeout
    
    if (keyIsDown) 
        key = KbName(find(keyCode));
        if ismember(key, {'k', 'd'})
            response_key {i} = key;
            response_time(i) = time;

            answered = true;
        
            if key == expected_key
        	    response_correct(i) = 1; % it's correct
            else
                response_correct(i) = 0; % it is not correct
            end
        end
    end
    
    %at this point, answered == false if they did not press a key (yet), or
    %if the key they pressed was not one of the two valid keys. You need to
    %figure out what to do in either case. That might involve a timeout.
end